picture of road salt storage - Bing images

 INTRODUCTION

Elevated chloride concentration in soil, groundwater and surface water is a growing concern, especially in states that treat roads with either sodium chloride, magnesium chloride or potassium chloride during winter months.  Another source of chloride is a water softener, which exchanges hardness ions with sodium.  Backwashing discharges sodium and chloride either into a sanitary sewer system, which ultimately flows to a waste water treatment plant (WWTP), or a private septic system.

Chloride, once introduced into a delicate ecosystem, can cause damage to freshwater plant life and organisms by increasing species mortality rates, disrupting reproductive patterns, and changing the entire ecosystem. These elements can also put a strain on plant respiration and change the composition and drinkability of our water supply. Sodium and chloride cannot be degraded or separated from the water during the treatment process other than through expensive processes like industrial reverse osmosis, so when salt-based water softeners are used its effects are often irreversible[1].

Reverse osmosis technology can be used to remove minerals in effluent, but it is usually cost prohibitive.  Upstream mitigation methods, i.e., using salt-free water softeners, can minimize the chloride concentration from entering the WWTP or a private septic system.

The US EPA has defined acute and chronic chloride limits for aquatic life as 230 mg/L and 860 mg/L, respectively. [2]

Many agencies are exploring alternatives to using the traditional road salt.  Interestingly, propylene glycol (used to de-ice aircraft) is being explored.  More interestingly, though, is that scientists have found insects and spiders in Alaska that create their own antifreeze proteins.[3]  Harnessing a natural alternative to traditional methods could be a great thing, so the next time you want to kill a spider, think about what wonders that spider could contribute to mankind!

January 24, 2021

Mr. Phillip Spranger

Wisconsin Department of Natural Resources

3911 Fish Hatchery Rd Fitchburg, WI 53711

 RE: Public Notice of Informational Hearing and Intent to reissue a Wisconsin Pollutant Discharge Elimination System (WPDES) Permit No. WI-0036552-06-0

 Dear Mr. Spranger:

 Environmental Review, Inc. has reviewed the Facility Specific Chloride Variance Data Sheet and has the following comments:

1) According to Section II, part C, sources for chloride include effluent from residential/commercial water softeners and inflow/intrusion of road salt. Are combined sewer systems utilized in the community? If so, wouldn’t sewer separation be relevant in order to mitigate chloride from entering the waste water plant?

2) According to Section III, the receiving water body is a wetland tributary to Pleasant Valley Creek, and finally to the LaCrosse River. According to part G, under low flow conditions, the effluent flow is either lost in the wetland through evapotranspiration or to ground water seepage.

a. Total Dissolved Solids will remain in the soil and impact shallow groundwater, and will also serve as a continual source of contamination (i.e., chloride) that could impact the LaCrosse River. Has any thought been given to installing shallow groundwater monitoring wells in order to assess impacts over time?

b. Should soil salinity be evaluated under current conditions and monitored?

c. Has any thought been given to evaluate the current specific conductance in either Pleasant Valley Creek or the LaCrosse River, and to monitor such over time?

3) According to Section VIII, part H, reverse osmosis and lime softening treatments were evaluated for end of pipe treatment for the removal of chloride. Is a revolving algal biofilm reactor a technology that could be considered?

Please direct your response to: This email address is being protected from spambots. You need JavaScript enabled to view it..

Sincerely, Barb Johnson, Associate in Minnesota

Senior Reviewer

Environmental Review, Inc. a 501(c)(3) Nonprofit Public Benefit Corporation, 1792 Rogers Avenue, San Jose, CA 95112, http://www.envreview.org/